Counterfeiting is seriously damaging for the customer, who may become deceived, and it is especially damaging for the industry as the products lose prestige, and brands can lose important amounts of their turnover due to these kinds of fraudulent practices. In specific cases such as chemicals and beverages, counterfeiting can also lead to severe security and health risks.
Proving if a product is genuine has been a continuous field of investigation. For more than a century, tamper evident seals has been designed with increasing complexity to avoid the sale of containers, envelopes, bottles and boxes with the unintended content. The target of a tamper seal is to show explicitly whether a first opening of a container has been done and to prevent the reuse of such container with non-genuine content.
Investigation to detect the opening of boxes or envelopes can be tracked back to the use of increasingly sophisticated wax seal. To prevent the re-use of container such as bottles, have led to investigation since many decades, e.g. GB191321357 or U.S. Pat. No. 1,038,023. Technical solutions difficult to counterfeit need to be renewed with technical progress and this field is in a constant evolution.
In a different field in the last decade new solutions have been proposed to secure security document such as passports, credit cards or banknotes by incorporating in the laminate structures optical waveguides or similarly called lightguides, which may be combined with zero-order filters or other security devices. These difficult to reproduce additional distinctive elements increase the complexity of such documents and are visually distinctive by machine vision or human eye, preventing forging of these documents. An example of these possibilities is disclosed in WO2011/072405. In this case an optical waveguide is used having specific optical features that can be recognised and the optical security device has to survive throughout the lifetime of the object in or on which it is adapted. It is not designed and engineered to be sensitive to changes in the environment but on the opposite to stay unchanged despite external stresses and aggressions.
Example of markets where products are sold thanks to the recognition of the packaging by the consumers, and not of its content, are the market of perfumes, pharmaceutics and high value alcoholic beverages, such as quality wine and spirits. For these markets, it is critical for the manufacturers to have distinctive packaging that counterfeiters cannot forge and copy easily and that cannot be re-used easily either. However, perfumes and alcoholic beverages are sold in jars and bottles that in most cases can be reused as the emptying of their content rarely lead to their destruction. Counterfeiting networks of beverages for example devote themselves to fill authentic bottles of known brands, with low-quality beverages and to re-capsulate them before selling said counterfeit bottles at below their usual price, many times also in the official channel, with the subsequent damage for the brands. From the packaging, it is only the capsule, which in some cases could distinguish them from genuine products. The same problem exists in the case of chemical or medical substances with an even higher danger, i.e. counterfeiting of the substances could lead to extremely severe security and health problems, as there is no control or hygiene in the counterfeiting business. The development of anti-counterfeit techniques and systems is an important industry sector as most brands attempt to protect themselves against this important fraud and some of them even invest up to 5% of their turnover both in anti-counterfeiting systems and components, and in undertaking legal actions.
Some security elements are the tags and seals surrounding both the bottle and the bottleneck. They can incorporate different security elements: security bottoms, encoded printing, iridescent printing, rosettes, anti-scanner and anti-photocopy colors, neutral response to ultraviolet light, luminescent fibers and ink that is only visible by means of its exposure to ultraviolet light, latent image, micro text, phosphorescent inks or even DNA code prints, allowing to certify the authenticity of extremely highly priced products). One of the drawbacks of security tags or seals is that they do not easily prevent the products from being counterfeited because they can be reproduced quite faithfully, without the consumer being able to detect the fraud or due to the fact that the original tags can be easily removed although special glues are used to stick them.
As counterfeiters constantly acquire new skills and technology, more and more complex solutions are put in place in this tamper seals. Simple printed elements adapted to bottle capsules such as reported in CA2398089 in FR2918966 are replaced with more complex systems such as reported in EP1857374, as example among many others. EP1857374 discloses for example a radiofrequency identification element, or RFID tag, adapted to a bottle cap and a separate radiofrequency detector. Any rupture or damage of the bottle part on which the RFID tag is adapted will cause destruction or malfunction in the detected radiofrequency signal, and so allows the detection of fraudulent manipulations. EP1857374 illustrates that these types of solutions are complex and not user-friendly for the average consumer, they are expensive and require specific readout equipment (a UV lamp or an RFID detector system for example).
Another example of a tamper seal presenting visible changes that indicate tampering attempts through delamination of a light diffusive layer is explained in US2004/0209028. The appearance of an optical seal such as disclosed in US2004/0209028 may lack a unique appearance feature or a specific function preventing forgers to replace such seals with forged labels having a similar overall appearance. Especially poor lighting conditions are possible in the retailing shops, or in the consumption establishments for the alcoholic beverages and the consumers may have limited access to information of how the packaging should look like.
For some applications such as for container locks, as disclosed in US 2008/0256991, a system has been proposed based on an optical waveguide wherein at one side an infrared emitter is arranged and wherein to the other end of the optical waveguide an infrared detector is incorporated. The detection of infrared light by the detector is used to detect for example attempts to break into the container or to detect that the container is locked in a proper way. Such a system is voluminous and it would be very difficult to miniaturise it and to adapt it to smaller objects such as bottles or small containers. Also, the system requires a light emitter and so also an energy source for that emitter, and the solution would also not be conceivable as anti-counterfeit for smaller and less expensive objects.
Another example of a system using an optical waveguide is disclosed in JP2002019338. This system is based on a monomode waveguide or a stack of monomode waveguide layers. As mentioned in JP2002019338, this system has various limitations. In this system, the plane wave from a laser is incoupled into a monomode waveguide thanks to a so-called light binding hologram (or a plurality of these holograms). The hologram in JP2002019338 is basically a grating patterning the monomode waveguide surface and can be called as well a resonant waveguide grating. JP2002019338 mentions in par.[0026] that the light source that can be used to control the seal must be a laser, preferably a visible-light laser. It must have a coherence length of several mm or more so that it constitutes substantially a plane wave impeding on the binding hologram [0031].
Using materials having common refractive indexes (˜1.5), as suggested in JP2002019338, the monomode waveguide core must have a thickness of 2.4 μm or less (see par. [0005]). The monomode waveguide core must be surrounded by two claddings having thicknesses of 6 μm or more to avoid cross-talks between monomode cores or light leakage by a fraction of the light escaping the waveguide (see par. [0005]). As the light-binding holograms require a coherent laser to be coupled to the monomode waveguide, only a monochromatic light source can be used which means that light sources such as sunlight, light bulbs, LEDs and other non monochromatic light sources cannot be used in the seal described in JP2002019338. This implies the requirement of an extremely precise alignment of the incident light beam to the light-binding holograms, as non-normal incidence will not couple light into the monomode waveguide. The required alignment precision of the incident angle of the impeding light beam on the hologram should be typically better than 2°, relative to the normal of to said light binding holograms. This could prove difficult in practical use to test infringement as tamper-evident seals can be used on objects of any shape and size. In consequence a very precise and complicated alignment system must be provided, or at least an alignment system must be designed and/or adapted for each differently shaped object to which a tamper-evident seal is fixed. More particularly, it would be extremely difficult, if not impossible, to hold by hand a laser source and perform the required illumination alignment precision of the incident light beam to the light-binding holograms in the system of JP2002019338.
Additionally, as the tamper seal proposed by JP2002019338 is designed to work with monomode waveguide(s), the identification and therefore the security of the seals relies in using several laminated monomode waveguides working at different laser wavelengths, or in using a spatially phase-modulated laser beam (also-called uneven beam or unevenness of the light-binding holograms). This in turns requires the modulated light to be aligned to the modulation of the unevenness of the light-binding holograms, either placed in the grating itself or in the cladding. The order of magnitude for this spatial phase modulation cited in JP2002019338 is between a few microns and a few tens of microns. Therefore, in order to control a seal, a trained professional must be equipped with the right laser (or different lasers and perform iteratively different controls) equipped with the right phase modulation optics and shine the laser (or the lasers) on a target of a milllimetric-range size, and he must align the laser source to invisible micron-size patterns and with an accurately normal incidence. In most anti-counterfeiting control situations, which can happen in hostile environment or must be performed in very limited timeframe, this would be highly impractical or in practice impossible to perform. Only trained and well-equipped professionals could perform such a control.